2. The background can be any image, though I was using a scan of a test target with colored patches for scanner calibration.

3.Create a layer "final target" on top of the background.Set contents to transparent.

4.Create a selection 295 pixels on a side with rectangular marquee tool.Position this selection in the upper left corner.

5.Save the selection to an alpha channel "Grid Box."

6.Run an action with the following steps.

a.Load the selection "Grid Box."

b.Select the layer "final target"

c.Expand the selection 2 pixels.

d.Fill the selection with the foreground color.

e.Set the foreground color to white.

f.Select the background layer.

g.Move the selection 295 pixels to the right.

h.Save the new selection as "Grid Box", replacing the channel.

The use of this action:

Use the eyedropper tool to select a color from the center of the selected square, then use the magic wand tool to subtract from the selection using the color in the center of the square in contiguous mode with tolerance set to 8.Then run the action, and repeat the above process in the next selected square.In the scan I am preparing, there is a grid of colored squares surrounded by a large black border.The final result needs the black border eliminated so that the colored squares completely butt up against each other spaced 295 pixels apart.

So by running the action, the color in the center of each box is copied to fill the rest of the square selected area that's black, leaving the center portion intact.The copied colors go on the "final target" layer so the background layer is not disturbed.

If you need a copy of the action and/or the image file, contact me by email.

Doesn't sound like you're doing anything that should be inherently slower, though that would be a fairly large image for a 32 bit system. What is the RAM situation on your computer and in Photoshop preferences, and what operating system are you running?

The one thing you mention in the step description that seems a little amiss is that you're expanding the selection each time you run the action.

As a fellow Photoshop user, I'll be happy to test your action comparitively on my CS5 and CS3 installs, but I'd rather not take the time to try to reproduce the action from the steps you've given in text. Why not post it online and provide a link here?

My OS is Windows XP Pro, SP3. 4GB RAM installed. CS5 version is 12.0.3. No third-party plugins are installed, and I disabled OpenGL with no effect.

My written description left out the fact that I re-saved the selection after moving it so it was not expanded repeatedly. I also tried using a path instead of a selection in an alpha channel but this did not improve the performance either. The upload action uses the path. If you're testing it, create a 295x295 pixel selection and save it as the path "Grid Box."

It might be cryptic just what I'm trying to do. The application is to calibrate a film scanner, and to do this one scans a test film with colored squares. Unfortunately due to the scanner optics only the center part of each color patch is usable, so it was necessary to mask off the outer portions of each square with a piece of dark plastic and then reconstruct an image that looks like the original test film where the outer portions of each square are the average color of the square's center. When I'm running the action I sample the center part of a square with the eyedropper tool, then use the magic wand tool to subtract the center part of the color patch from the selection to create a new selection that looks like a square ring that the action fills with the foreground color. Then it steps one square to the right and the process repeats for the next color patch.

The file is large, but if it is a system configuration issue it seems strange that CS3 can handle this yet CS5 cannot when it's marketed as having improved attention to performance.

My theory initially was that you had given Photoshop just enough RAM to work efficiently with your CS3 setup, but perhaps because of differences in your Photoshop RAM setting or perhaps because Photoshop CS5 has more code in memory, it's starving for RAM under the same test, and goes to its scratch file for relief.

I created a test image and tried your action with a stopwatch.

Photoshop CS5 x64 on Windows 7 x64 (i.e., with plenty of RAM) takes 1.8 seconds to run through your action.

Photoshop CS5 32 bit consistently takes 6.8 seconds to go through the same steps. Notably it stalls on the Expand and Select layer "Background" steps for a few seconds each, where it blazed right through them in the 64 bit version.

In my case I have given Photoshop CS5 2897 MB to work with (89%). This number is larger on a 64 bit system than what you can set because Photoshop 32 bit can use up to a 3 GB address space.

Photoshop CS5 32 bit consistently takes 6.8 seconds to go through the same steps. Notably it stalls on the Expand and Select layer "Background" steps for a few seconds each, where it blazed right through them in the 64 bit version.

I'll clarify this a bit...

When the Action step Expand is highlighted and the action is stalled for a few seconds, the History menu is actually showing Fill. When the Action step Select layer "Background" is highlighted for a few seconds, the History step is still showing Deselect.

Chris, did you test with both 32 and 64 bit Photoshop CS5? There's definitely something going on here with 32 bit CS5. I see it write a large amount of data to its scratch file, by the way.

Good catch. There is no delay using the Play arrow button, but F10 stalls. I can't find anything about F10 being already assigned and the Action code allows me to assign it. Somehow, it's an evil shortcut key. Windows documentation says F10 "activates the menu bar in the active program." So it could be that it's hooked by the OS and should therefore not be allowed in Photoshop, or PS isn't hooking the key properly to prevent Windows from trapping it.

More to the point: Code in CS5 is dealing with the keypress differently from the way CS3 did it.